Make it work with coffee-script > 1.7.0

http://coffeescript.org/ -> Change Log -> 1.7.0
> When requiring CoffeeScript files in Node you must now explicitly register the compiler. This can be done with require `coffee-script/register` or `CoffeeScript.register()`. Also for configuration such as Mocha's, use `coffee-script/register`.

I checked with 1.6.3. Seems to be working well, but check it please yourself just in case.
Thx.